A gerotor operates using inner and outer rotors that rotate about their respective axes within a housing. A drive mechanism synchronizes the rotors so that they do not touch. As the rotors rotate, teeth of the inner rotor and lobes of the outer rotor move relative to each other to create voids between the teeth of the inner rotor and the lobes of the outer rotor that open, reach a maximum volume, and then close. Fluid enters and leaves the voids through gaps (referred to as ports) between the lobes of the outer rotor.
The housing comprises four regions. A first of the four regions forms an inlet duct for the gerotor system. A second of the four regions forms an outlet duct for the gerotor system. The third and fourth of the four regions are located between the inlet duct region and the outlet duct region and have small clearances between inner and outer rotors and the housing. These two regions operate to prevent fluid flow around the outside of the outer rotor between the inlet duct and the outlet duct.
For a gerotor system operating as a compressor, input power to the drive mechanism drives the rotors. A fluid enters from the inlet duct of the housing through one or more intake ports as the void opens. Once the fluid is captured, the void volume decreases, causing the pressure of the fluid to increase. After a desired pressure (generated by the geometries of the two rotors) is achieved, the fluid exits through one or more outlet ports into the outlet duct of the housing.
For a gerotor system operating as an expander, high-pressure fluid enters from the inlet duct of the housing through one or more intake ports into a small void in the gerotor. The fluid is captured, and the fluid pressure operates on the rotors to cause the void volume to increase as the fluid pressure decreases. The expanding fluid causes the rotors to turn. After a desired pressure is achieved, the fluid exits through one or more outlet ports into the outlet duct of the housing. The rotation of the rotors produces output power from the gerotor drive mechanism.
Gerotor compressors and expanders have several advantages that apply to both gerotor compressors and expanders, such as the following:
No valves;
Low vibration;
Compact;
Efficient;
Tolerant of liquid;
Low manufacturing cost;
High pressure ratio per stage;
Rotational speed matches conventional engines, motors, and generators;
Low parts count;
Oil-free operation; and
Operates efficiently at varying speeds